Exposure apparatus and device manufacturing method

ABSTRACT

An exposure apparatus which projects and transfers a pattern formed on a mask to a substrate using exposure light includes a stage, an optical system, and a gas stream forming mechanism which forms a stream of inert gas in an optical path space including a space which is located between the stage and the optical system and through which the exposure light passes. In addition, a member forms a predetermined space between the optical path space and a peripheral space outside the optical path space in the exposure apparatus, and a gas supply mechanism supplies the inert gas into the predetermined space.

FIELD OF THE INVENTION

The present invention relates to an exposure apparatus which projectsand transfers a pattern formed on a mask to a substrate using exposurelight, and a device manufacturing method.

BACKGROUND OF THE INVENTION

In photolithography for manufacturing a semiconductor element or thelike, an exposure apparatus which projects and exposes a pattern imageon a mask (e.g., a reticle) to a photosensitive substrate through aprojecting optical system is used. Semiconductor integrated circuitsdeveloped recently are aiming at micropatterning. In photolithography,photolithography light sources are going to have shorter wavelengths.

However, when vacuum UV light and, more particularly, light having awavelength shorter than 250 nm, e.g., harmonic light of a KrF excimerlaser (wavelength: 248 nm), an ArF excimer laser (wavelength: 193 nm),F₂ laser (wavelength: 157 nm), or a YAG laser is used as exposure light,the intensity of exposure light decreases due to the influence ofexposure light absorption by oxygen, and the like.

To avoid the decrease in exposure light transmittance, a conventionalexposure apparatus having a light source such as an F₂ excimer laserforms a sealed space where only an optical path portion is sealed andreplaces the gas in the sealed space with a gas such as nitrogencontaining no oxygen.

FIGS. 14A and 14B are views showing an exposure apparatus which performsexposure by supplying an inert gas to a space between a photosensitivesubstrate (wafer) and the final optical member of a projecting opticalsystem (lens barrel) to form an inert gas atmosphere in the space. Inthis exposure apparatus, to separate the space on the exposure regionfrom the ambient atmosphere, a shielding member is arranged around thespace, and the inert gas is supplied from the periphery of the exposureregion into the space.

In the exposure apparatus shown in FIGS. 14A and 14B, however, theatmosphere in the space cannot be replaced with the inert gas until theatmosphere at the step or gap around the wafer moves into the space. Inexposing the periphery of the wafer, the inert gas concentration in thespace decreases. In addition, when the wafer stage moves at a highspeed, the inert gas concentration decreases due to the influence ofinvolvement, resulting in a variation in illuminance.

A similar problem is posed when an inert gas is supplied to theperiphery of a reticle. In exposing the periphery of the reticle, theinert gas concentration in the space decreases. In addition, when thewafer stage moves at a high speed, the inert gas concentration decreasesdue to the influence of involvement, resulting in a variation inilluminance.

SUMMARY OF THE INVENTION

The present invention has been made in consideration of the aboveproblems, and has as its object to provide an exposure apparatus whichcan stabilize the inert gas concentration in a container thataccommodates various members including an illumination system, aprojecting lens system, and mechanical members, and a devicemanufacturing method.

According to the present invention, the foregoing object is attained byproviding an exposure apparatus which projects and transfers a patternformed on a mask to a substrate using exposure light, comprising:

a stage;

an optical system;

a gas stream forming mechanism which forms a stream of an inert gas inan optical path space including a space which is located between thestage and the optical system and through which the exposure lightpasses; and

a member which is arranged between the stage and a portion around thegas stream forming mechanism to form a predetermined space thatmaintains an average inert gas concentration P satisfyingP2<P<P1where P1 is an average concentration of the inert gas present in theoptical path space, and P2 is an average concentration of the inert gaspresent outside the optical path space.

According to the present invention, the foregoing object is attained byproviding an exposure apparatus which projects and transfers a patternformed on a mask to a substrate using exposure light, comprising:

a stage;

an optical system;

a gas stream forming mechanism which forms a stream of an inert gas inan optical path space including a space which is located between thestage and the optical system and through which the exposure lightpasses; and

a member which forms a predetermined space between the optical pathspace and a peripheral space outside the optical path space in theexposure apparatus,

wherein a width of the member in a direction of the stream of the inertgas is not less than twice a distance between the member and the stage.

In a preferred embodiment, the member is formed around the optical pathspace.

In a preferred embodiment, the member has at least one of a groovearranged outside the optical path space to surround the optical pathspace.

In a preferred embodiment, the width of the member in the direction ofthe stream of the inert gas is not less than three times the distancebetween the member and the stage.

In a preferred embodiment, the member is arranged upstream of the gasstream with respect to the optical path space.

In a preferred embodiment,

the apparatus performs exposure while scanning the mask and thesubstrate, and

the member is arranged in a direction of scanning with respect to theoptical path space.

In a preferred embodiment, the member has a concave portion at a portionagainst the stage on an upstream side of the gas stream in the opticalpath space.

In a preferred embodiment, the apparatus further comprises a supply portwhich supplies an inert gas to the predetermined space, wherein thesupply port is arranged on an upstream side of the gas stream in theoptical path space.

In a preferred embodiment, the member is formed around the optical pathspace.

In a preferred embodiment, the member has at least one of a groovearranged outside the optical path space to surround the optical pathspace.

According to the present invention, the foregoing object is attained byproviding an exposure apparatus which projects and transfers a patternformed on a mask to a substrate using exposure light, comprising:

a stage;

an optical system;

a gas stream forming mechanism which forms a stream of an inert gas inan optical path space including a space which is located between thestage and the optical system and through which the exposure lightpasses; and

a member which forms a predetermined space between the optical pathspace and a peripheral space outside the optical path space in theexposure apparatus,

wherein a distance between the member and the stage is shorter than thatbetween the stage and an optical element of the optical system, which isclosest to the stage.

In a preferred embodiment, the distance between the member and the stageis not more than ½ that between the stage and the optical element of theoptical system, which is closest to the stage.

In a preferred embodiment, the distance between the member and the stageis not more than ¼ that between the stage and the optical element of theoptical system, which is closest to the stage.

In a preferred embodiment, the member is arranged upstream of the gasstream with respect to the optical path space.

In a preferred embodiment, the apparatus performs exposure whilescanning the mask and the substrate, and

the member is arranged in a direction of scanning with respect to theoptical path space.

In a preferred embodiment, the member has a concave portion at a portionagainst the stage on an upstream side of the gas stream in the opticalpath space.

In a preferred embodiment, the apparatus further comprises a supply portwhich supplies an inert gas to the predetermined space, wherein thesupply port is arranged on an upstream side of the gas stream in theoptical path space.

In a preferred embodiment, the member is formed around the optical pathspace.

In a preferred embodiment, the member has at least one of a groovearranged outside the optical path space to surround the optical pathspace.

According to the present invention, the foregoing object is attained byproviding an exposure apparatus which projects and transfers a patternformed on a mask to a substrate using exposure light, comprising:

a stage;

an optical system;

a gas stream forming mechanism which forms a stream of an inert gas inan optical path space including a space which is located between thestage and the optical system and through which the exposure lightpasses;

a member which forms a predetermined space between the optical pathspace and a peripheral space outside the optical path space in theexposure apparatus; and

a gas supply mechanism which supplies the inert gas into thepredetermined space.

In a preferred embodiment, the gas supply mechanism is branched from thegas stream forming mechanism.

In a preferred embodiment, a position at which the gas supply mechanismsupplies the inert gas into the predetermined space is located upstreamof the gas stream in the predetermined space with respect to the opticalpath space.

In a preferred embodiment, the apparatus performs exposure whilescanning the mask and the substrate, and

the member is arranged in a direction of scanning with respect to theoptical path space.

In a preferred embodiment, the member has a concave portion at a portionagainst the stage on an upstream side of the gas stream in the opticalpath space.

In a preferred embodiment, the apparatus further comprises a supply portwhich supplies an inert gas to the predetermined space, wherein thesupply port is arranged on an upstream side of the gas stream in theoptical path space.

In a preferred embodiment, the member is arranged upstream of the gasstream with respect to the optical path space.

In a preferred embodiment, the member is formed around the optical pathspace.

In a preferred embodiment, the member has at least one of a groovearranged outside the optical path space to surround the optical pathspace.

According to the present invention, the foregoing object is attained byproviding an exposure apparatus which projects and transfers a patternformed on a mask to a substrate using exposure light, comprising:

a stage;

an optical system;

a gas stream forming mechanism which supplies an inert gas into anoptical path space including a space which is located between the stageand the optical system and through which the exposure light passes; and

a member which forms a predetermined space between the optical pathspace and a peripheral space outside the optical path space in theexposure apparatus,

wherein the member forms, in the predetermined space, at least onegroove having a width in a direction of a stream of the inert gas.

In a preferred embodiment, the apparatus further comprises a gas supplymechanism which supplies the inert gas from the at least one groove.

In a preferred embodiment, the member has a plurality of partitioningmembers arranged to surround the optical path space.

The distance from the lower end of the partitioning members to thesubstrate is preferably substantially equal to the distance from thelower end of the shielding member of the gas stream forming mechanism tothe substrate.

The lower surface of the member preferably has at least one groove alongthe outer periphery of the optical path space.

The groove preferably becomes deeper as it is separated from the centerof the gas stream forming mechanism.

The supply port and exhaust port of the gas stream forming mechanism andtheir channel are preferably formed in the member.

The member preferably has inside an opening which extends from the gaschannel to the groove.

Part of the shielding member preferably has an opening.

The exhaust amount of the gas in the gas stream forming mechanism ispreferably smaller than the supply amount of the gas.

The apparatus preferably further comprises an exhaust unit whichexhausts the inert gas that leaks from the gas stream forming mechanismthrough the predetermined space together with the ambient atmosphere.

The inert gas can be nitrogen gas or helium gas.

The gas stream forming mechanism is preferably arranged to form thestream of the inert gas in the optical path space between the projectingoptical system and the substrate. The member is preferably arranged toform the predetermined space between the stage and a portion around thegas stream forming mechanism.

The gas stream forming mechanism is preferably arranged to form thestream of the inert gas in the optical path space between anillumination optical system which illuminates the mask and a mask stagewhich holds the mask. The member is preferably arranged to form thepredetermined space between the stage and a portion around the gasstream forming mechanism.

The gas stream forming mechanism is preferably arranged to form thestream of the inert gas in the optical path space between the projectingoptical system and a mask stage which holds the mask. The member ispreferably arranged to form the predetermined space between the stageand a portion around the gas stream forming mechanism.

The gas stream forming mechanism may have a first gas stream formingmechanism which is arranged to form the stream of the inert gas in afirst optical path space between the projecting optical system and thesubstrate, a second gas stream forming mechanism which is arranged toform the stream of the inert gas in a second optical path space betweenthe illumination system which illuminates the mask and the mask stagewhich holds the mask, and a third gas stream forming mechanism which isarranged to form the stream of the inert gas in a third optical pathspace between the mask stage and the projecting optical system. Themember may be arranged to form the predetermined space between the stageand portions around the first to third gas stream forming mechanisms.

The supply port and exhaust port of the gas stream forming mechanism andtheir channel may be formed in the member.

The inert gas may be supplied from the member to the substrate. Supplyof the inert gas from the member to the substrate and supply of theinert gas into the optical path space are preferably independently orcommonly performed. The lower portion of the member preferably has atleast one groove.

An exposure apparatus which projects and transfers a pattern formed on amask to a substrate using exposure light preferably comprises:

a stage;

an optical system; and

a gas stream forming mechanism which supplies an inert gas into anoptical path space including a space between the stage and the opticalsystem where the exposure light passes through,

wherein the gas stream forming mechanism comprises a restricting memberin the optical path space in a direction from the optical system to thesubstrate.

The gas stream forming mechanism may have two opposing supply ports at aposition close to the optical system in the optical path space, and asupply port and an exhaust port opposing each other at a position closeto the substrate in the optical path space, and

the restricting member may be installed between the two pairs ofsupply/exhaust ports in a direction substantially along a gas stream.

The gas stream forming mechanism may have a supply port and an exhaustport opposing each other at a position close to the optical system inthe local space, and the restricting member may be a plate memberinstalled on the substrate side of the supply port outlet or exhaustport inlet in a direction almost along the gas stream. Alternatively,the gas stream forming mechanism may have two opposing supply ports at aposition close to the optical system in the local space, and therestricting member may be a plate member installed on the substrate sideof the supply port outlet in a direction almost along the gas stream.

As a device manufacturing method using the above-described exposureapparatus, the following methods are also incorporated in the presentinvention. A device manufacturing method comprises the steps of exposinga substrate using the above exposure apparatus, and developing theexposed substrate.

Other features and advantages of the present invention will be apparentfrom the following description taken in conjunction with theaccompanying drawings, in which like reference characters designate thesame or similar parts throughout the figures thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing part of an exposure apparatus according to thefirst embodiment of the present invention;

FIG. 2 is a view showing a modification of the exposure apparatus shownin FIG. 1 according to the first embodiment of the present invention;

FIG. 3 is a view showing another modification of the exposure apparatusshown in FIG. 1 according to the first embodiment of the presentinvention;

FIG. 4 is a view showing the modification in FIG. 3 viewed from thelower side;

FIG. 5 is a view showing part of an exposure apparatus according to thesecond embodiment of the present invention;

FIG. 6 is a view showing a modification of the exposure apparatus shownin FIG. 5 according to the second embodiment of the present invention;

FIG. 7 is a view showing part of another exposure apparatus according tothe second embodiment of the present invention;

FIG. 8 is a view showing part of an exposure apparatus according to thethird embodiment of the present invention;

FIG. 9 is a view showing a modification of the exposure apparatus shownin FIG. 8 according to the third embodiment of the present invention;

FIG. 10 is a view showing another exposure apparatus according to thethird embodiment of the present invention;

FIG. 11 is a view showing part of an exposure apparatus according to thefourth embodiment of the present invention including the periphery of areticle;

FIG. 12 is a flow chart of the overall manufacturing process of asemiconductor device;

FIG. 13 is a flow chart of the overall manufacturing process of asemiconductor device;

FIG. 14A is a view showing part of a conventional exposure apparatus;

FIG. 14B is a view showing part of the conventional exposure apparatus;

FIG. 15 is a view showing part of an exposure apparatus according to thefifth embodiment of the present invention;

FIG. 16 is a view of the exposure apparatus of the fifth embodimentshown in FIG. 15, which is viewed from the lower side at the position ofthe opening plate;

FIG. 17 is a view showing part of another exposure apparatus accordingto the fifth embodiment of the present invention;

FIG. 18 is a view showing a modification of the exposure apparatus shownin FIG. 16 according to the fifth embodiment of the present invention;

FIG. 19 is a view showing another modification of the exposure apparatusshown in FIG. 16 according to the fifth embodiment of the presentinvention;

FIG. 20 is a view showing part of still another exposure apparatusaccording to the fifth embodiment of the present invention;

FIG. 21 is a view of the exposure apparatus of the fifth embodimentshown in FIG. 20, which is viewed from the lower side at the position ofthe opening plate;

FIG. 22 is a view showing part of still another exposure apparatusaccording to the fifth embodiment of the present invention;

FIG. 23 is a view showing part of still another exposure apparatusaccording to the fifth embodiment of the present invention;

FIG. 24 is a view showing part of still another exposure apparatusaccording to the fifth embodiment of the present invention;

FIG. 25 is a view showing part of an exposure apparatus according to thesixth embodiment of the present invention;

FIG. 26 is a view showing the sixth embodiment of the present inventionfrom which the arrangement shown in FIG. 1 is omitted;

FIG. 27 is a view showing a modification of the exposure apparatus shownin FIG. 2 according to the sixth embodiment of the present invention;

FIG. 28 is a view showing another modification of the exposure apparatusshown in FIG. 2 according to the sixth embodiment of the presentinvention;

FIG. 29 is a view showing still another modification of the exposureapparatus shown in FIG. 2 according to the sixth embodiment of thepresent invention;

FIG. 30 is a view showing still another modification of the exposureapparatus shown in FIG. 2 according to the sixth embodiment of thepresent invention;

FIG. 31 is a view showing still another modification of the exposureapparatus shown in FIG. 2 according to the sixth embodiment of thepresent invention;

FIG. 32 is a view showing part of an exposure apparatus according to theseventh embodiment of the present invention; and

FIG. 33 is a view showing an example in which a gas stream formingapparatus is installed in the space between the illumination opticalsystem and the reticle in the sixth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments of the present invention will be describedbelow with reference to the accompanying drawings.

[First Embodiment]

FIG. 1 is a view showing part of an exposure apparatus according to thefirst embodiment of the present invention.

This exposure apparatus has a light source such as an F₂ excimer laser(not shown) which generates a short-wavelength laser beam asillumination light. The illumination light (exposure light) from thelight source uniformly illuminates a reticle (mask) through anappropriate illumination optical member. The light (exposure light)transmitted through the reticle reaches, through various optical membersof a projecting optical system 101, the surface of a wafer 103 placed ona wafer stage 102, and forms a reticle pattern on the wafer surface.

The wafer stage 102 having the wafer 103 placed thereon is designed tobe movable in three-dimensional directions (X, Y, and Z directions). Thereticle pattern is sequentially projected and transferred onto the wafer103 by a so-called step-and-repeat scheme that repeats stepping movementand exposure. Even when the present invention is applied to a scanningexposure apparatus, the arrangement is almost the same as describedabove.

For exposure, a heated and/or cooled inert gas (e.g., nitrogen gas,helium gas, or the like) is supplied from a supply port 113 through asupply valve 111 to a space (to be referred to as an optical path spacehereinafter) 116 between the wafer 103 and a shielding member 115 on thelower side of the projecting optical system 101, including the spacethrough which the exposure light passes and the periphery of the space.The inert gas supplied to the optical path space 116 is partiallyrecovered from an exhaust port 114 and exhausted through an exhaustvalve 112. The supply valve 111, supply port 113, exhaust port 114, andexhaust valve 112 constitute an example of a gas stream formingmechanism which forms a stream of a gas such as an inert gas in theoptical path space 116.

Arrows in FIG. 1 indicate the flow of the inert gas. To transmitalignment light, the shielding member 115 partially has a transparentmember.

Basically, the optical path space 116 is set at a positive pressure withrespect to the ambient atmosphere (the pressure in the optical pathspace 116 is made higher than that in the ambient atmosphere), therebydecreasing the oxygen concentration in the exposure atmosphere in theoptical path space. For this reason, the amount of inert gas that leaksfrom the optical path space 116 to the peripheral space is more than theexhaust amount through the exhaust valve 112. The inert gas that hasleaked from the optical path space 116 is recovered and exhausted by anexhaust unit 122 together with the ambient atmosphere supplied from asupply unit 121.

The inert gas that has leaked from the optical path space 116 isrecovered and exhausted by the exhaust unit 122 together with theambient atmosphere supplied as a heated and/or cooled gas (dry air or aninert gas having a low concentration) is supplied from the supply unit121. The temperature around the exposure region is adjusted by theambient atmosphere.

Opening/closing and the degrees of valve opening of the supply valve 111and exhaust valve 112 are controlled by an environment controller 131.Since the supply valve 111 and exhaust valve 112 are normally open, theinert gas is always supplied into the optical path space 116independently of the position of the stage 102. However, when the stage102 is detached from the lower side of the optical path space 116 to dowafer exchange or maintenance, control may be performed to temporarilystop inert gas supply or reduce the supply amount. Supply may be startedor the supply amount may be increased after wafer exchange or after theend of maintenance before the stage 102 moves to the lower side of theoptical path space 116 again.

The environment controller 131, a stage controller 132, and othercontrollers (not shown) are systematically controlled by a maincontroller 133 in various kinds of operations including wafer exchange,alignment operation, and exposure operation. The control contents by themain controller 133 and the operation state of the exposure apparatusare monitored by a monitoring device 134.

If the atmosphere in the gap around the wafer 103 or at the step portionon the wafer stage 102 in the region that enters or leaves the opticalpath space 116 is insufficiently replaced, the ambient atmosphere may beinvolved in the optical path space when the wafer stage 102 moves. Thismay increase the oxygen concentration in the optical path space 116.

In the first embodiment, a member 151 is arranged to limit the height ofthe space around the optical path space 116 (especially, the space nearthe optical path space 116) and to form a predetermined space 150. LetP1 be the average concentration of the inert gas present in the opticalpath space 116, and P2 be the average concentration of the inert gaspresent outside the optical path space. The predetermined space 150 thatsurrounds the optical path space 116 is formed between the member 151and the wafer 103 so that an average inert gas concentration P thatsatisfiesP2<P<P1 (a first condition)is maintained. The concentration in the predetermined space 150 near theoptical path space 116 is almost equal to the inert gas concentration inthe optical path space 116. Toward the outer periphery of thepredetermined space 150, the concentration becomes closer to that of theexternal atmosphere. In other words, the member 151 forms a gap space tothe wafer 103, thereby forming the space having the average inert gasconcentration P.

The distance H1 from the lower surface (wafer-side surface) of themember 151 for forming the predetermined space 150 to the wafer is setto ½ or less, or more preferably, ⅓ or less of the width L1 of the lowersurface of the member 151 in a predetermined direction substantiallyparallel to the wafer (a second condition). (The distance may be thedistance to the wafer stage. An expression “the distance between themember 151 or another member and the wafer” in the following descriptionis equivalent to “the distance between the member 151 or another memberand the wafer stage.” Even for the reticle, the “reticle” can bereplaced with the “reticle stage). Then, since the gas hardly flows inthe predetermined space, the gas such as oxygen that absorbs exposurelight is involved in the optical path space 116 at a low probability.The above “predetermined direction substantially parallel to the wafer”may be “the direction of a straight line at which the planeperpendicular to the wafer, including the direction of gas supply fromthe supply port 113, and the plane including the wafer surface crosseach other”, i.e., the “direction of gas stream in the optical pathspace” or the “scanning exposure direction of the wafer stage 102”.

In addition, the height H1 of the predetermined space 150 (the distancebetween the wafer and the lower surface of the member 151) is preferablyless than the distance between the wafer and the optical element of theprojecting optical system 101, which is closest to the wafer (a thirdcondition). Preferably, the height of the predetermined space 150 is ½,and more preferably, ¼ the distance between the wafer and the opticalelement of the projecting optical system 101, which is closest to thewafer. Accordingly, the place where the inert gas concentration becomeslow can be separated from the optical path space 116, so the inert gasconcentration around the optical path space 116 can be stabilized at ahigh concentration.

The predetermined space 150 may be formed in the optical path space 116only on the upstream side of the gas stream in the optical path space116 (on the supply port side in the optical path space 116). Thepredetermined space 150 may be formed on both the upstream anddownstream sides of the gas stream in the optical path space 116. Thepredetermined space 150 may be formed around the optical path space 116.

As a modification, a partitioning member 152 that forms thepredetermined space 150 and also partitions the optical path space 116may be designed, as shown in FIG. 2. The partitioning member 152 isarranged such that the distance between the wafer and the lower surfaceof the partitioning member 152 becomes shorter than that between thewafer and the optical element of the projecting optical system, which isclosest to the wafer. As similar to the above second condition in themodification, when the ratio of the distance H1 from the lower end ofthe member 152 that forms the predetermined space 150 to the wafer 103to the width L1 (the width in the direction substantially parallel tothe wafer) of the member 152 that forms the predetermined space 150 isrepresented by 1: X, X is preferably 2 or more and, more preferably, 3or more. If the X is less than 2, the inert gas concentration under themember 152 that forms the predetermined space 150 becomes considerablylow, although it changes depending on the flow speed of the ambientatmosphere, the flow speed of the inert gas that leaks from the opticalpath space 116, and the driving speed of the wafer stage 102. When theheight is limited, the inert gas that has leaked from the optical pathspace 116 hardly flows. With the collected inert gas, the influence ofinvolvement when the wafer stage 102 moves is suppressed, and theatmosphere collected around the wafer 103 is replaced. Accordingly, theinert gas concentration in the purge space can be stabilized.

Alternatively, as shown in FIGS. 3 and 4, an opening plate 158 thatsatisfies the above ratio may be arranged under the optical path space116. FIG. 3 is a sectional view of an exposure apparatus in which theopening plate 158 is arranged under the optical path space 116surrounded by a glass member 104 that passes alignment light and by theprojecting optical system 101, and the predetermined space 150 (FIG. 2)is formed under the opening plate 158. FIG. 4 is a view of the openingplate 158 viewed from the lower side. In this embodiment, the exhaustport 114 is arranged, though it is not always necessary. A supply portmay be formed in place of the exhaust port 114.

The inert gas is supplied from the supply port 113 into the optical pathspace 116. At the same time, the inert gas may also be supplied to thepredetermined space 150 by branching a pipe from the supply means forsupplying the gas to the supply port or using another supply means. Thepredetermined space 150 to which the inert gas is supplied is preferablya predetermined space on the upstream side of the gas stream in theoptical path space 116.

[Second Embodiment]

In the second embodiment, the member that forms a predetermined space150 has, at its lower portion, partitioning members 153 that surroundthe periphery of an optical path space 116 multiple-fold (twofoldtogether with a shielding member 115 in FIG. 5) as shown in FIG. 5. Whenan inert gas that has leaked from the optical path space 116 iscollected in a groove (a concave portion) formed by the partitioningmembers 153, the atmosphere collected at the step and gap around a wafer103 can be replaced. In addition, the influence of involvement by awafer stage 102 or the influence of ambient atmosphere can besuppressed. Especially, in FIG. 5, the partitioning member 153 isarranged outside the optical path space 116 to surround the optical pathspace 116. Referring to FIG. 5, the distance from the lower end of thepartitioning member 153 to the wafer 103 is substantially equal to thatfrom the lower end of the shielding member 115 to the wafer 103.However, the distances may be different.

As a modification, FIG. 6 shows an arrangement having a plurality ofpartitioning members 153. As the number of partitioning members 153increases, the concentration of the collected inert gas can be increasedtoward the optical path space 116. Hence, the atmosphere in the grooveor at the step around the wafer 103 can be replaced at a more separatedportion of the optical path space 116. For this reason, the inert gasconcentration in the optical path space 116 can be stabilized at ahigher concentration.

As another modification, when a member 154 having a plurality of groovesis arranged under the partitioning member 152 that forms thepredetermined space 150 of the first embodiment shown in FIG. 1, asshown in FIG. 7, the same effect as described above can be obtained. Thegrooves are arranged to surround the optical path space 116multiple-fold, like the partitioning member 152 or partitioning members153 shown in FIG. 5 or 6. The depth of the groove is preferably equal toor less than the height from the final optical member under a projectingoptical system 101 to the wafer 103. If the groove is too deep,replacement in the groove requires time. Hence, a long time is requiredto replace the atmosphere collected in the gap or at the step around thewafer 103.

The distance between the partitioning member 153 and the shieldingmember 115 that shields the optical path space 116 from the ambientatmosphere in FIG. 5, the distance between the shielding member 115 andone of the partitioning members 153, which is most closed to the opticalaxis of the projecting optical system 101, in FIG. 6, or the width ofthe member 154 in a plane parallel to the page surface and including theoptical axis of the projecting optical system (in other words, theabove-described width in “a direction substantially parallel to thewafer”) in FIG. 7 is preferably equal to or more than twice the distancebetween the wafer and one of the lower ends of the shielding member 115and partitioning members 153, which is closest to the wafer, in FIG. 5or 6, or equal to or more than twice the distance between the wafer andthe lower surface of the member 154 in FIG. 7. More preferably, thedistance is not twice but three times or more.

The inert gas is supplied from the supply port 113 into the optical pathspace 116. At the same time, the inert gas may also be supplied to oneor a plurality of predetermined spaces 150 by branching a pipe from thesupply means for supplying the gas to the supply port or using anothersupply means (FIGS. 9 and 10 to be described later). The predeterminedspace 150 to which the inert gas is supplied is preferably apredetermined space 150 arranged on the upstream side of the gas streamin the optical path space 116. For the exhaust side as well, the gas maybe exhausted from the predetermined space 150 in a similar way. For theexhaust side, the gas is preferably exhausted from the predeterminedspace 150 arranged on the downstream side of the gas stream.

[Third Embodiment]

In the third embodiment, the member 154, supply port 113, and exhaustport 114 of the second embodiment shown in FIG. 7 are integrated to forma member 155 having a supply port 163 and an exhaust port 164 inside, asshown in FIG. 8. With this arrangement, the number of components can bereduced. As for the depths of the grooves formed in the member 155, thegroove around an optical path space 116 is shallowest, i.e., the groovesbecome shallow inside the member 155 centered on the optical path space116 and deep outside.

The inner grooves of the member 155 are made shallow to shorten thereplacement time at the inner part and maintain a high concentration atthe inner part. The outer grooves of the member 155 are made deep toincrease the volume and to suppress a decrease in inert gasconcentration due to entrance of ambient atmosphere because the outerpart is readily influenced by the ambient atmosphere, and the internalinert gas concentration abruptly decreases due to a transient change ifthe volume is small. Transient phenomena include abrupt reverse drivingof a wafer stage 102 or entrance of a step or groove around the wafer103 into the optical path space 116.

In FIG. 8, the grooves formed in the member 155 become shallow towardthe optical path space 116. Instead of changing the depth, even when thewidth of the groove is increased outward from the optical path space116, the same effect as described above can be obtained.

As a modification, when a member 156 having openings 157 that extendfrom the supply port 163 and exhaust port 164 in the member 155 shown inFIG. 8 to the multiple grooves is arranged, as shown in FIG. 9, theatmosphere in the grooves can be effectively replaced. In this case, theopenings 157 to the grooves must be much smaller than the openings ofthe supply port 163 and exhaust port 164. When the openings 157 arelarge, the atmosphere in the grooves enters the supply port 163 andexhaust port 164 to decrease the inert gas concentration in the opticalpath space 116. In addition, the openings 157 corresponding to thegrooves preferably become smaller outward.

To decrease the number of components, the member that forms thepredetermined space 150, the supply port, and the exhaust port may beintegrated even as shown in FIG. 1 or 2 of the first embodiment or FIG.5 of the second embodiment.

As another modification, to increase the exhaust efficiency in theoptical path space 116, as shown in FIG. 10, a shielding member 125 isformed by forming openings 126 in the shielding member 115 that formsthe optical path space 116 in the arrangement of the second embodimentshown in FIG. 6 such that the inert gas that has leaked from theopenings 126 can blow in the partitioning members 153, like the inertgas that has leaked from the lower side of the optical path space 116.

In this case, when the openings 126 are formed at portions where theflow speed in the optical path space 116 decreases, the exhaustefficiency in the optical path space 116 can be increased. Accordingly,the replacement time in the optical path space 116 can be shortened. Thedistance from the lower end of the partitioning members 153 to the wafer103 is preferably larger than the distance from the lower end of theshielding member 125 to the wafer 103.

In the above embodiments, the optical path space 116 has an exhaustport. When recovery of ambient atmosphere is taken into consideration,the exhaust port may be used as another supply port. When the exhaustport is used as a supply port, the influence of ambient atmosphere canbe further suppressed even when the consumption amount is keptunchanged.

[Fourth Embodiment]

The present invention applied to the space between the projectingoptical system and the wafer stage in the first to third embodiments canalso be applied to the space between an illumination optical system anda reticle stage and the space between the reticle stage and theprojecting optical system. FIG. 11 is a view showing an exposureapparatus in which the present invention is applied to the space betweenthe projecting optical system and the wafer stage, the space between theillumination optical system and the reticle stage, and the space betweenthe reticle stage and the projecting optical system.

In the exposure apparatus shown in FIG. 11, for a first optical pathspace 314 between a final optical member (cover glass) 311 of aprojecting optical system 302 and a wafer chuck 303 (wafer 305), a firstsupply unit 341 which supplies an inert gas to the first optical pathspace 314 through a supply valve 312 and a first exhaust unit 342 whichexhausts the inert gas and the like from the first optical path space314 through an exhaust valve 313 are arranged. A member 501 which formsa first predetermined space 401 for limiting the height around the firstoptical path space 314 is arranged. With this arrangement, a portionwhere the inert gas concentration decreases can be separated from thefirst optical path space 314, and the inert gas concentration around thefirst optical path space 314 can be stabilized at a high concentration.

For a second optical path space 326 between an illumination opticalsystem 301 which illuminates a reticle (mask) 322 and a reticle stage(reticle 322) 321, a second supply unit 351 which supplies an inert gasto the second optical path space 326 through a supply valve 327 and asecond exhaust unit 352 which exhausts the inert gas and the like fromthe second optical path space 326 through an exhaust valve 328 arearranged. A member 502 which forms a second predetermined space 402 forlimiting the height around the second optical path space 326 isarranged. With this arrangement, a portion where the inert gasconcentration decreases can be separated from the second optical pathspace 326, and the inert gas concentration around the second opticalpath space 326 can be stabilized at a high concentration.

For a third optical path space 325 between the reticle stage 321 and theprojecting optical system 302, a third supply unit 345 which supplies aninert gas to the third optical path space 325 through a supply valve 323and a third exhaust unit 346 which exhausts the inert gas and the likefrom the third optical path space 325 through an exhaust valve 324 arearranged. A member 503 which forms a third predetermined space 403 forlimiting the height around the third optical path space 325 is arranged.With this arrangement, a portion where the inert gas concentrationdecreases can be separated from the third optical path space 325, andthe inert gas concentration around the third optical path space 325 canbe stabilized at a high concentration.

In this way, the inert gas concentration around the first to thirdoptical path spaces 314, 326, and 325 can be stabilized at a highconcentration.

As in the first embodiment, in the exposure apparatus shown in FIG. 11,opening/closing and the degrees of valve opening of the supply andexhaust valves are controlled by an environment controller (not shown).The reticle stage 321 is controlled by a stage controller (not shown) insynchronism with a wafer stage 304. The environment controller, stagecontroller, and other controllers (not shown) are systematicallycontrolled by a main controller (not shown) in various kinds ofoperations including wafer exchange, alignment operation, and exposureoperation. The control contents by the main controller and the operationstate of the exposure apparatus are monitored by a monitoring device(not shown).

The form of formation of the predetermined space for maintaining theaverage concentration P of the inert gas may be replaced with thatdescribed in the second or third embodiment.

[Fifth Embodiment]

FIG. 15 is a view showing part of an exposure apparatus according to thefifth embodiment of the present invention.

An inert gas is supplied from a supply port 113 through a supply valve111 into an optical path space 116. The inert gas supplied into theoptical path space 116 is partially recovered from an exhaust port 114through an exhaust valve 112.

When the inert gas is supplied from one direction, the amount of inertgas that leaks from the optical path space 116 to a predetermined space150 is larger in the +X direction (exhaust port side). If the distancefrom an opening plate 157 to the surface of a wafer 103 is long, theleakage amount difference becomes conspicuous. A supply port whichinjects the inert gas from the lower surface of the wafer 103 is added.FIG. 16 is a view of the opening plate 157 in FIG. 15, which is viewedfrom the lower side (−Y direction). When slit-like openings are added tothe supply port 113 and opening plate 157, the inert gas concentrationin the predetermined space 150 on the lower side of the supply port 113can be stabilized at a high concentration.

As a modification, supply of the inert gas to the optical path space 116and supply of the inert gas to the predetermined space 150 may beseparated, and the supply amounts may be controlled by separate massflow controllers MFC1 and MFC2, as shown in FIG. 17. In FIG. 15, whenthe inert gas is supplied from the opening into the predetermined space150, the atmosphere around the stage is involved at the time of stagemovement. The inert gas concentration near the opening decreases, andeven the inert gas concentration in the supply port 113 may sometimesdecrease. However, when the supply systems are separated, as shown inFIG. 17, the concentration of the inert gas supplied from the supplyport 113 can be stabilized at a high concentration.

In FIG. 16, a slit-like opening is formed. As a modification, when anarc opening is arranged to surround the optical path space 116, as shownin FIG. 18, the influence of the atmosphere around the optical pathspace 116 can be further suppressed.

As still another modification, as shown in FIG. 19, a groove may beformed on the predetermined space 150 side of the place where theopening plate 157 shown in FIG. 16 has openings, and a plurality ofopenings (five openings in FIG. 19) may be formed in the groove toinject the inert gas from the opening plate 157 to the wafer surfaceside. When the distance from the opening plate 157 to the surface of thewafer 103 is as short as 2 mm or less, the groove is filled with theinert gas. Hence, the inert gas concentration in the predetermined space150 on the lower side of the supply port 113 can be stabilized at a highconcentration. The size of the opening shown in FIG. 19 can be minimizedas compared to the size of the opening shown in FIG. 16. For thisreason, even when the ambient atmosphere is involved, the decrease ininert gas to the supply source can be suppressed.

In FIGS. 18 and 19 as well, the inert gas may be commonly supplied tothe optical path space 116 and predetermined space 150, as shown in FIG.15. Alternatively, as shown in FIG. 17, supply of the inert gas to theoptical path space 116 and supply of the inert gas to the predeterminedspace 150 may be separated. When the supply amounts are controlled bythe separate mass flow controllers MFC1 and MFC2, the concentration ofthe inert gas supplied from the supply port 113 can be stabilized at ahigh concentration.

FIGS. 20 and 21 show still another modification. In this modification, agroove that surrounds the optical path space 116 is formed in theopening plate 157 of the embodiment shown in FIG. 15 or 16. When thedistance from the opening plate 157 to the surface of the wafer 103 isas short as 2 mm or less, the groove is filled with the inert gas.Hence, the inert gas concentration around the optical path space 116 canbe stabilized at a high concentration. Alternatively, as shown in FIG.22, when an opening from which the inert gas is injected may be added tothe lower portion of the exhaust port 114 in the embodiment shown inFIG. 17. In this case, even when the ambient atmosphere is involved fromthe exhaust port side, the decrease in inert gas concentration can besuppressed. Referring to FIG. 22, the supply amounts can be differentmass flow controllers MFC1, MFC2, and MFC3. Hence, the flow rates can beoptimized in accordance with the arrangement.

As shown in FIG. 23, a groove that surrounds the optical path space 116may be formed in the opening plate 157, and a plurality of openings (10openings in FIG. 23) may be formed in the groove to inject the inert gasfrom the opening plate 157 to the wafer surface side. Alternatively, asshown in FIG. 24, grooves that partially surround the optical path space116 may be formed, and a plurality of openings (10 openings in FIG. 24)may be formed in the groove to inject the inert gas from the openingplate 157 to the wafer surface side.

In FIGS. 23 and 24 as well, the inert gas may be commonly supplied tothe optical path space 116 and predetermined space 150, as shown in FIG.15. Alternatively, as shown in FIG. 22, supply of the inert gas to theoptical path space 116 and supply of the inert gas to the predeterminedspace 150 may be separated. When the supply amounts are controlled bythe separate mass flow controllers MFC1, MFC2, and MFC3, theconcentration of the inert gas supplied from the supply port 113 can bestabilized at a high concentration.

The above embodiments assume that the supply amount of the inert gas tothe optical path space 116 is set to be equal to or more than theexhaust amount. If the optical path space is not set to a positivepressure, the optical path space draws the ambient atmosphere. Hence,the inert gas concentration in the optical path space decreases, and theexposure light transmittance decreases. However, in the arrangementsshown in FIGS. 23 and 24, inert gas supply to the optical path space 116is separated from inert gas supply to the predetermined space 150, andthe supply amounts are controlled by the separate mass flow controllersMFC1, MFC2, and MFC3. In this case, even when the pressure in theoptical path space 116 is lower than that in the predetermined space150, the inert gas concentration in the optical path space can bestabilized at a high concentration by setting the inert gas supplyamount to the predetermined space 150 to be larger. For this reason, theexhaust amount can be increased, and contamination generated from thewafer surface at the time of exposure can be efficiently exhausted.

The opening plate 157 need not be independently prepared. Instead, anopening portion may be formed in the supply means or exhaust means.

The distance between the opening plate 157 (lower surface (wafer-sidesurface) of the supply means or exhaust means) and the wafer is set to ½or less, or more preferably, ⅓ or less of the width corresponding to thedistance between the outer periphery of the optical path space 116 andthat of the opening plate 157 in a predetermined direction substantiallyparallel to the wafer. In this case, since the gas hardly flows in thepredetermined space, the gas such as oxygen that absorbs exposure lightis involved in the optical path space 116 at a low probability.

In addition, the height of the predetermined space 150 (the distancebetween the wafer and the lower surface of the opening plate 157) ispreferably less than the distance between the wafer and the opticalelement of a projecting optical system 101, which is closest to thewafer. Preferably, the height of the predetermined space 150 is ½ orless, and more preferably, ¼ or less the distance between the wafer andthe optical element of the projecting optical system 101, which isclosest to the wafer. Accordingly, the place where the inert gasconcentration becomes low can be separated from the optical path space116, so the inert gas concentration around the optical path space 116can be stabilized at a high concentration.

The predetermined space 150 may be formed in the optical path space 116only on the upstream side of the gas stream in the optical path space116 (on the supply port side in the optical path space 116). Thepredetermined space 150 may be formed on both the upstream anddownstream sides of the gas stream in the optical path space 116. Thepredetermined space 150 may be formed around the optical path space 116.

In the above first to fifth embodiments, an exposure apparatus isarranged to satisfy the first to third conditions, so that the effectsof each of the first to fifth embodiments will be more remarkable.

[Sixth Embodiment]

FIGS. 25 and 26 are views showing part of an exposure apparatusaccording to the sixth embodiment of the present invention. Thisexposure apparatus has a light source such as an F₂ excimer laser (notshown) which generates a short-wavelength laser beam as illuminationlight. The illumination light (exposure light) from the light sourceuniformly illuminates a reticle (mask) through an appropriateillumination optical member. The light (exposure light) transmittedthrough the reticle reaches, through various optical members of aprojecting optical system, the surface of a wafer placed on a waferstage installed in a chamber having a supply unit and an exhaust unit,and forms a reticle pattern on the wafer surface.

The wafer stage having the wafer placed thereon is designed to bemovable in three-dimensional directions (X, Y, and Z directions). Thereticle pattern is sequentially projected and transferred onto the waferby a so-called step-and-repeat scheme that repeats stepping movement andexposure. Even when the present invention is applied to a scanningexposure apparatus, the arrangement is almost the same as describedabove.

For exposure, an inert gas (e.g., nitrogen gas, helium gas, or the like)whose temperature and impurity concentration are accurately managed issupplied from a supply port through a supply valve to a local space,including the space through which the exposure light passes in the gasstream forming apparatus on the lower side of the projecting opticalsystem and the periphery of the space. The inert gas supplied to thelocal space is partially recovered from an exhaust port and exhaustedthrough an exhaust valve. Arrows in FIG. 25 indicate the flow of theinert gas.

Basically, the local space is set at a positive pressure with respect tothe ambient atmosphere (the pressure in the local space is made higherthan that in the ambient atmosphere), thereby decreasing the oxygenconcentration in the exposure atmosphere in the local space. For thisreason, the amount of inert gas that leaks from the local space to theperipheral space is more than the exhaust amount through the exhaustvalve. The inert gas that has leaked from the local space is recoveredand exhausted by an exhaust unit together with the chamber atmospheresupplied from a supply unit. The temperature and impurity concentrationof the chamber atmosphere in the local space containing the exposureatmosphere are accurately managed by the gas stream forming apparatus.Hence, the gas supplied from the supply unit can be a gas whosetemperature and impurity concentration are managed moderately as much aspossible.

Opening/closing and the degrees of valve opening of the supply valve andexhaust valve are controlled by an environment controller. Since thesupply valve and exhaust valve are normally open, the inert gas isalways supplied into the local space independently of the position ofthe stage. However, when the stage is detached from the lower side ofthe local space to do wafer exchange or maintenance, control may beperformed to temporarily stop inert gas supply or reduce the supplyamount. Supply may be started or the supply amount may be increasedafter wafer exchange before the stage moves to the lower side of thelocal space again.

The environment controller, a stage controller, and other controllers(not shown) are systematically controlled by a main controller invarious kinds of operations including wafer exchange, alignmentoperation, and exposure operation. The control contents by the maincontroller and the operation state of the exposure apparatus aremonitored by a monitoring device.

If the atmosphere in the gap around the wafer 103 or at the step portionon the wafer stage in the region that enters or leaves the local spaceis insufficiently replaced, the ambient atmosphere may be involved inthe optical path space when the wafer stage moves. This may increase theoxygen concentration in the local space.

In the sixth embodiment, to maintain the oxygen concentration in thelocal space to the set value or less, the gas stream forming apparatusis installed on the projecting optical system side while separated fromthe wafer by a narrow space. A distance H1 of the narrow space betweenthe gas stream forming apparatus and the wafer is preferably equal to orless than ½, or more preferably, ⅕ of a distance H0 of the local spacebetween the projecting optical system and the wafer. Accordingly, theoxygen concentration in the local space can be maintained to the setvalue or less. A length L1 of the narrow space along the gas stream ispreferably set to twice or more, and preferably three times more, of thedistance H1.

For the outer shape of the gas stream forming apparatus, the section ofthe gas stream forming apparatus shown in FIG. 25 may be extended in thedepth direction of the purge surface. The gas stream forming apparatusmay alternatively have a rotationally symmetrical shape with respect tothe exposure optical axis. The outer shape is not particularly limitedto the above shapes.

In the local space, for example, an organic gas may be generated fromthe resist applied to the wafer. The organic gas may react with exposurelight and contaminate the surface of the lens of the projecting opticalsystem. This may fog the lens and decrease the exposure light intensity.

To prevent this, in the sixth embodiment, a restricting member whichpartially reduces the sectional area of the local space in a directionfrom the projecting optical system to the wafer is arranged at theoutlet of the supply port in the local space. The narrow spacesuppresses any vortex flow generated when the gas in the local spacemoves from the wafer side to the projecting optical system side along anaxis corresponding to the vertical direction of the page surface. Hence,the organic gas or the like generated from the resist applied to thewafer is quickly exhausted. Since the concentration of the organic gasreaching the lens of the projecting optical system can be sufficientlyreduced, fogging on the lens can be suppressed. In addition, since theinert gas in the local space smoothly flows, the oxygen concentration inthe local space can be more quickly reduced.

The installation position of the restricting member is not limited tothe supply side of the local space, as shown in FIG. 26. The restrictingmember may be arranged on the exhaust side, as shown in FIG. 27, or onboth the supply and exhaust sides, as shown in FIG. 28.

As a modification, the exhaust mechanism in FIG. 27 may be changed to asupply mechanism having opposing supply ports in the local space, and arestricting member may be arranged at each supply port, as shown in FIG.29. In this case, the inert gas supply amounts from the supply ports,and the lengths and positions of the restricting members need not alwaysbe symmetrical. An asymmetrical arrangement (the restricting membershave different heights in the optical axis direction of the projectingoptical system) shown in FIG. 30 can more effectively preventcontamination.

As another modification, instead of arranging a restricting member, anotch portion removing the wafer-side part of the gas stream formingapparatus near the supply port is installed to partially widen thenarrow space, as shown in FIG. 31. With this arrangement, the sameeffect as that obtained by arranging the restricting member can beexpected.

In this embodiment, the restricting member is fixed. However, a drivingmechanism for moving the restricting member may be added to move therestricting member in accordance with the exposure state. In this case,for example, when the stage should be moved without performing exposure,the projecting amount of the restricting member can be increased toprevent any decrease in inert gas concentration. During exposure, therestricting member can be retracted not to shield the exposure light.

In this embodiment, the projecting optical system, wafer, and the waferstage have been described in detail. The present invention can also beapplied to the illumination optical system, reticle, and reticle stage,as shown in FIG. 33.

[Seventh Embodiment]

In the seventh embodiment, two supply/exhaust systems are prepared inthe gas stream forming apparatus, as shown in FIG. 32. Two supply portsoppose each other on the projecting optical system side. A supply portand an exhaust port oppose each other on the wafer side. A restrictingmember is arranged between the two pairs of supply ports/exhaust ports.

According to this arrangement, the two opposing supply ports and exhaustports on the projecting optical system side suppress an impurity gaswhich is generated from the resist applied to the wafer and reaches theprojecting optical system. Hence, the impurity gas can be quicklyexhausted by the gas stream formed by the supply port and exhaust porton the wafer side.

Each of the supply/exhaust system on the projecting optical system sideand that on the wafer side may have both the supply port and exhaustport.

In the above sixth and seventh embodiments, an exposure apparatus isarranged to satisfy the first to third conditions, so that the effectsof each of the first to fifth embodiments will be more remarkable.

[Application Example of Exposure Apparatus]

A semiconductor device manufacturing process using the above exposureapparatus will be described next.

FIG. 11 shows the flow of the overall manufacturing process of asemiconductor device.

In step 1 (circuit design), the circuit of a semiconductor device isdesigned. In step 2 (mask preparation), a mask is prepared on the basisof the designed circuit pattern. In step 3 (wafer manufacture), a waferis manufactured using a material such as silicon. In step 4 (waferprocess), called a preprocess, an actual circuit is formed on the waferby lithography using the mask and wafer.

In step 5 (assembly), called a post-process, a semiconductor chip isformed from the wafer prepared in step 4. This step includes processessuch as assembly (dicing and bonding) and packaging (chipencapsulation). In step 6 (inspection), inspections including anoperation check test and a durability test of the semiconductor devicemanufactured in step 5 are performed. A semiconductor device iscompleted with these processes and shipped in step 7.

FIG. 13 shows details of the wafer process.

In step 11 (oxidation), the surface of the wafer is oxidized. In step 12(CVD), an insulating film is formed on the wafer surface. In step 13(electrode formation), an electrode is formed on the wafer bydeposition. In step 14 (ion implantation), ions are implanted into thewafer. In step 15 (resist process), a photosensitive agent is applied tothe wafer. In step 16 (exposure), the circuit pattern is transferred tothe wafer using the above exposure apparatus. In step 17 (development),the exposed wafer is developed. In step 18 (etching), portions otherthan the developed resist image are etched. In step 19 (resist removal),any unnecessary resist remaining after etching is removed. By repeatingthese steps, a multilayered structure of circuit patterns is formed onthe wafer.

As many apparently widely different embodiments of the present inventioncan be made without departing from the spirit and scope thereof, it isto be understood that the invention is not limited to the specificembodiments thereof except as defined in the appended claims.

1. An exposure apparatus which projects and transfers a pattern formedon a mask to a substrate using exposure light, comprising: a stage; anoptical system; a gas stream forming mechanism which forms a stream ofan inert gas in an optical path space including a space which is locatedbetween said stage and said optical system and through which theexposure light passes; and a member which is arranged between said stageand a portion around said gas stream forming mechanism to form apredetermined space that maintains an average inert gas concentration PsatisfyingP2<P<P1  where P1 is an average concentration of the inert gas presentin the optical path space, and P2 is an average concentration of theinert gas present outside the optical path space.
 2. The apparatusaccording to claim 1, wherein said member is formed around the opticalpath space.
 3. The apparatus according to claim 2, wherein said memberhas at least one of a groove arranged outside the optical path space tosurround the optical path space.
 4. A device manufacturing method,comprising the steps of: exposing a substrate using an exposureapparatus of claim 1; and developing the exposed substrate.
 5. Anexposure apparatus which projects and transfers a pattern formed on amask to a substrate using exposure light, comprising: a stage; anoptical system; a gas stream forming mechanism which forms a stream ofan inert gas in an optical path space including a space which is locatedbetween said stage and said optical system and through which theexposure light passes; and a member which forms a predetermined spacebetween the optical path space and a peripheral space outside theoptical path space in the exposure apparatus, wherein a width of saidmember in a direction of the stream of the inert gas is not less thantwice a distance between said member and said stage.
 6. The apparatusaccording to claim 5, wherein said member is formed around the opticalpath space.
 7. The apparatus according to claim 6, wherein said memberhas at least one groove arranged outside the optical path space tosurround the optical path space.
 8. The apparatus according to claim 5,wherein the width of said member in the direction of the stream of theinert gas is not less than three times the distance between said memberand said stage.
 9. The apparatus according to claim 5, wherein saidmember is arranged upstream of the gas stream with respect to theoptical path space.
 10. The apparatus according to claim 5, wherein theapparatus performs exposure while scanning the mask and the substrate,and said member is arranged in a direction of scanning with respect tothe optical path space.
 11. The apparatus according to claim 5, whereinsaid member has a concave portion at a portion against the stage on anupstream side of the gas stream in the optical path space.
 12. Theapparatus according to claim 5, further comprising a supply port thatsupplies an inert gas to the predetermined space, wherein said supplyport is arranged on an upstream side of the gas stream in the opticalpath space.
 13. The apparatus according to claim 5, wherein said memberis formed around the optical path space.
 14. The apparatus according toclaim 13, wherein said member has at least one groove arranged outsidethe optical path space to surround the optical path space.
 15. A devicemanufacturing method, comprising the steps of: exposing a substrateusing an exposure apparatus of claim 5; and developing the exposedsubstrate.
 16. An exposure apparatus which projects and transfers apattern formed on a mask to a substrate using exposure light,comprising: a stage; an optical system; a gas stream forming mechanismwhich forms a stream of an inert gas in an optical path space includinga space which is located between said stage and said optical system andthrough which the exposure light passes; and a member which forms apredetermined space between the optical path space and a peripheralspace outside the optical path space in the exposure apparatus, whereina distance between said member and said stage is shorter than thatbetween said stage and an optical element of said optical system, whichis closest to said stage.
 17. The apparatus according to claim 16,wherein the distance between said member and said stage is not more than½ that between said stage and the optical element of said opticalsystem, which is closest to said stage.
 18. The apparatus according toclaim 16, wherein the distance between said member and said stage is notmore than ¼ that between said stage and the optical element of saidoptical system, which is closest to said stage.
 19. The apparatusaccording to claim 16, wherein said member is arranged upstream of thegas stream with respect to the optical path space.
 20. The apparatusaccording to claim 16, wherein the apparatus performs exposure whilescanning the mask and the substrate, and said member is arranged in adirection of scanning with respect to the optical path space.
 21. Theapparatus according to claim 16, wherein said member has a concaveportion at a portion against the stage on an upstream side of the gasstream in the optical path space.
 22. The apparatus according to claim16, further comprising a supply port that supplies an inert gas to thepredetermined space, wherein said supply port is arranged on an upstreamside of the gas stream in the optical path space.
 23. A devicemanufacturing method, comprising the steps of: exposing a substrateusing an exposure apparatus of claim 16; and developing the exposedsubstrate.
 24. An exposure apparatus which projects and transfers apattern formed on a mask to a substrate using exposure light,comprising: a stage; an optical system; a gas stream forming mechanismwhich forms a stream of an inert gas in an optical path space includinga space which is located between said stage and said optical system andthrough which the exposure light passes; a member which forms apredetermined space between the optical path space and a peripheralspace outside the optical path space in the exposure apparatus; and agas supply mechanism which supplies the inert gas into the predeterminedspace.
 25. The apparatus according to claim 24, wherein said gas supplymechanism is branched from said gas stream forming mechanism.
 26. Theapparatus according to claim 24, wherein a position at which said gassupply mechanism supplies the inert gas into the predetermined space islocated upstream of the gas stream in the predetermined space withrespect to the optical path space.
 27. The apparatus according to claim24, wherein the apparatus performs exposure while scanning the mask andthe substrate, and said member is arranged in a direction of scanningwith respect to the optical path space.
 28. The apparatus according toclaim 24, wherein said member has a concave portion at a portion againstthe stage on an upstream side of the gas stream in the optical pathspace.
 29. The apparatus according to claim 24, further comprising asupply port that supplies an inert gas to the predetermined space,wherein said supply port is arranged on an upstream side of the gasstream in the optical path space.
 30. The apparatus according to claim24, wherein said member is arranged upstream of the gas stream withrespect to the optical path space.
 31. The apparatus according to claim24, wherein said member is formed around the optical path space.
 32. Theapparatus according to claim 31, wherein said member has at least onegroove arranged outside the optical path space to surround the opticalpath space.
 33. A device manufacturing method, comprising the steps of:exposing a substrate using an exposure apparatus of claim 24; anddeveloping the exposed substrate.
 34. An exposure apparatus whichprojects and transfers a pattern formed on a mask to a substrate usingexposure light, comprising: a stage; an optical system; a gas streamforming mechanism which supplies an inert gas into an optical path spaceincluding a space which is located between said stage and said opticalsystem and through which the exposure light passes; and a member whichforms a predetermined space between the optical path space and aperipheral space outside the optical path space in the exposureapparatus, wherein said member forms, in the predetermined space, atleast one groove having a width in a direction of a stream of the inertgas.
 35. The apparatus according to claim 34, further comprising a gassupply mechanism which supplies the inert gas from said at least onegroove.
 36. The apparatus according to claim 34, wherein said member hasa plurality of partitioning members arranged to surround the opticalpath space.
 37. The apparatus according to claim 36, wherein said memberhas at least one groove arranged outside the optical path space tosurround the optical path space.
 38. A device manufacturing method,comprising the steps of: exposing a substrate using an exposureapparatus of claim 34; and developing the exposed substrate.
 39. Anexposure apparatus which projects and transfers a pattern formed on amask to a substrate using exposure light, comprising: a stage; anoptical system; and a gas stream forming mechanism which supplies aninert gas into an optical path space including a space which is locatedbetween said stage and said optical system and through which theexposure light passes, wherein said gas stream forming mechanismcomprises a restricting member for restricting a stream of said inertgas in a direction from said optical system to an optical axis of saidoptical system.
 40. The apparatus according to claim 39, wherein saidgas stream forming mechanism comprises a first gas stream formingmechanism having two opposing supply ports or opposing a supply and anexhaust ports in the optical path space, and a second gas streammechanism having a supply port and an exhaust port opposing each otherat a position closer to the stage than said first gas stream formingmechanism in the optical path space, and said restricting member isinstalled between the first and second gas stream forming mechanisms.41. A device manufacturing method, comprising the steps of: exposing asubstrate using an exposure apparatus of claim 39; and developing theexposed substrate.
 42. An exposure apparatus which projects andtransfers a pattern formed on a mask to a substrate using exposurelight, comprising: a stage for placing the substrate; an optical systemfor guiding a light from the pattern to the substrate, wherein saidoptical system has a plurality of optical elements; and a member whichis arranged around a final optical element of said plurality of opticalelements which is closest to said stage, wherein a lower surface of saidmember is substantially parallel to an upper surface of said stage,wherein a distance between said lower surface of said member and saidupper surface of said stage is not more than one half of a width of saidmember in a predetermined direction substantially parallel to the uppersurface of said stage.
 43. The apparatus according to claim 42, whereinthe distance between said lower surface of said member and said uppersurface of said stage is not more than one third of a width of saidmember in a predetermined direction substantially parallel to the uppersurface of said stage.
 44. The apparatus according to claim 42, furthercomprising a plurality of surrounding fluid supply ports for supplying afluid to a space between said member and said stage.
 45. The apparatusaccording to claim 42, further comprising a plurality of surroundingfluid supply ports for supplying a fluid to a space between said memberand said stage, and wherein said plurality of surrounding fluid supplyports is arranged to surround an optical path space which is a lightpath of a light passed from said final optical element to saidsubstrate.
 46. The apparatus according to claim 42, further comprising aplurality of surrounding fluid supply ports for supplying a fluid to aspace between said member and said stage, and wherein said plurality ofsurrounding fluid supply ports is arranged in a space surrounded by saidmember and said stage.
 47. The apparatus according to claim 42, whereina groove is formed in said member to surround an optical path spacewhich is a light path of a light passed from said final optical elementto said substrate.
 48. The apparatus according to claim 47, wherein aninner portion of said groove comprises a plurality of surrounding fluidsupply ports for supplying a fluid to a space between said member andsaid stage.
 49. The apparatus according to claim 42, further comprisingan optical path space fluid supply port for supplying a fluid to anoptical path space which is a light path of a light passed from saidfinal optical element to a said substrate.
 50. The apparatus accordingto claim 49, wherein said optical path space fluid supply port isarranged in the optical path space.
 51. A device manufacturing method,comprising: exposing a substrate using an exposure apparatus of claim42; and developing the exposed substrate.
 52. An exposure apparatuswhich projects and transfers a pattern formed on a mask to a substrateusing exposure light, comprising: a first stage for placing the mask; asecond stage for placing the substrate; an optical system for guiding alight from the pattern to the substrate, said optical system arrangedbetween said first stage and said second stage and having a plurality ofoptical elements; and a member which is arranged around an optical pathspace which is a light path of a light passed from a final opticalelement of said plurality of optical elements which is closest to saidstage, to said substrate, wherein a lower surface of said member issubstantially parallel to an upper surface of said second stage; and aplurality of surrounding fluid supply ports for supplying a fluid to aspace between said member and said second stage, wherein the pluralityof surrounding fluid supply ports is arranged to surround the opticalpath space, wherein a distance between said lower surface of said memberand said upper surface of said second stage is not more than one thirdof a width of said member in a predetermined direction substantiallyparallel to the upper surface of said second stage.
 53. A devicemanufacturing method, comprising: exposing a substrate using an exposureapparatus of claim 52; and developing the exposed substrate.
 54. Anexposure apparatus which projects and transfers a pattern formed on amask to a substrate using exposure light, comprising: a stage forplacing the substrate; an optical system for guiding a light from thepattern to the substrate, wherein said optical system has a plurality ofoptical elements, and an optical path space is formed between a finaloptical element of said plurality of optical elements which is closestto said stage, and said substrate; and a member which is arranged aroundsaid final optical element of said plurality of optical elements, whichis closest to said stage, wherein a lower surface of said member issubstantially parallel to an upper surface of said stage, and asurrounding space is formed between said member and said stage; and aplurality of surrounding fluid supply ports for supplying a fluid to aspace between said member and said stage, wherein, when an outer spaceis defined by a space outside of the optical path space and thesurrounding space, a concentration of the fluid in the optical pathspace is higher than a concentration of the fluid in the surroundingspace, and a concentration of the fluid in the surrounding space ishigher than a concentration of the fluid in the outer space.
 55. Theapparatus according to claim 54, wherein said plurality of surroundingfluid supply ports is arranged to surround the optical path space.
 56. Adevice manufacturing method, comprising: exposing a substrate stageusing an exposure apparatus of claim 54; and developing the exposedsubstrate.